Max height

1. The problem statement, all variables and given/known data
A ball is thrown upwards. Its velocity at 3/5 its max height is 16.0m/s
What is its initial velocity?
What is its max height?

2. Relevant equations
vf^2 = vi^2 -2g(yf-yi)

define up as positive

3. The attempt at a solution

I ran through numerous attempts on paper but can't seem to find a proper answer. The closest I got was an answer that spit out a negative height.... help? Somewhat urgent as I need to bring this question in tomorrow for homework.

Two issues here being that
a) the units do not match since I haven't multiplied in height, so operations may be difficult
b) there is a negative, so the height will come out as a negative, which seems illogical as I have specified up as positive

No, that was a typo. I fixed it. Stated in the original post that up was to be positive. Therefore the acceleration is negative.
Thank you for your comment on the units but the height still appears to turn out negative.

Staff: Mentor

No, that was a typo. I fixed it. Stated in the original post that up was to be positive. Therefore the acceleration is negative.
Thank you for your comment on the units but the height still appears to turn out negative.

Then you've introduced an excess negative by both subtracting the term 2gh and making the constant g negative.

You can either treat g as a positive constant and account for the direction in the algebra, or you can make "2ad" a positive term and let g be negative to account for the direction.